My family has unlimited everything, so essentially I (don't) pay $40 for the additional line and unlimited (5GB) data on my Omnia. Almost every carrier has a 5GB "cap" - they don't actually cut you off, they just throttle your speed down to dial-up levels. 5GB of data is generally more than enough for a phone, if you use more they assume you're tethering to a PC, etc., and penalize you. You can pay $45 for the "truly" unlimited data, at least on Verizon, unless that has changed. When comparing phone plans in general (take off the Droid), the iPhone has the most expensive plan. Also, I'm pretty sure T-Mobile has billshrink in their pocket, so the whole idea of the site is to make other providers look really expensive.